Electrical switch



United States Patent Claims priority, application Germany Aug. 24, 19592 Claims. (Cl. 200--145) ri`his invention relates to electric switchesof the kind comprising a switch pin which moves axially in a quenchingchamber containing quenching medium and draws arcs which generatepressure in the quenching medium so that the latter is caused to flowpast and quench the arcs.

The invention is intended to provide an improved switch of the kindreferred to, arranged so that the arc or arcs are not drawn out to suchan extent that the rise of pressure in the quenching medium isexcessive. In some known switches excessive rise of pressure leads torupturing of the quenching chamber.

According to the invention a switch of the kind referred to ischaracterised in that the switch pin comprises conducting parts andinsulating parts, and fixed contacts and terminals are arranged so thatin operation the conducting parts of the switch pin draw from thecontacts arcs which are in series with one another and then the arcsmove and burn in gaps between the terminals and are there subjected tothe action of the quenching medium as the latter is flowing towards oneor more outlets of the quenching chamber. Further and optional featuresof the invention appear from the following description and claims.

Two switches according to the invention are illustrated by way ofexample in sectional elevation in the accompanying drawing. i

The switch shown in FlG. l comprises a quenching chamber 1 filled withquenching medium and accommodating xed contacts, 2, 3, 4 and 5 and anaxiallymovable switch pin consisting of conducting parts 6 and 7 andinsulating parts 8 and 9.

The switch pin slides axially in guides 10 and 11 in the quenchingchamber 1. Y

The iixed contacts 3, 4 are connected to each other through a conductingtube 12 provided with terminals 14 and 15.

A fixed terminal 13 has an aperture forming an outiiow opening forquenching medium in the quenching chamber 1, and also has an aperture inwhich the switch pin slides.

A tixed terminal 16 on the Contact 5 is below a narrow passage 17 formedin an insulating mass, and this passage 17 is open through a slot 18formed so that an arc between the contacts 4 and 5 can be guided to theterminals and 16. The space accommodating the terminal 14 communicatesthrough a slot 19 with the space between the terminal 2 and contact 3.

In order to compel the arcs drawn between the parts 2 and 3 and betweenthe parts 4 and 5 to strike over on tov the terminals 13, 14 and 15, 16respectively, the spacing of the terminals from one another is less thanthat of the contacts 2, 3 and 4, 5.

The tube 12 constituting the connection between the contacts 3 and 4contains a volume of quenching medium which is not subjected directly toheating by the arcs.

The guides 10 and 11 for the switch pin are always closed by the switchpin.

The switch is shown in the closed position, the path of the currentbeing through the contact 2, the part 6, the contact 3, the tube 12, thecontact 4, the part 7, and the contact 5.

On opening of the switch the switch pin moves upwards, and two arcs aredrawn between the switch pin parts 6 and 7 and the fixed contacts 3 and5. The roots of the arcs on the iixed contacts 3 and 5 immediatelytravel through the slots 19 and 18 to the terminals 14 and 16respectively.

The two arcs now burn one between the switch pin part 6 and the terminal14 and the other between the switch pin part 7 and the terminal 16.

On further movement of the switch pin, rstly the lower end of the switchpin part 6 comes into the vicinity of the terminal 13, so that the rootof the arc burning on the switch pin part 6 jumps over on to theterminal 13 and the arc now burns between the terminals 13 and 14.

On further movement of the switch pin the lower end of the switch pinpart '7 comes into the vicinity of the terminal 15 so that the root ofthe lower arc jumps to the terminal 15 and the arc burns between theterminals 15 and 16.

Pressure in the quenching medium is generated immediately on drawing ofthe arcs by the switch pin, and this pressure is maintained and built upto the desired maX- imum pressure values due to the length of the arcbetween the terminals 15 and 16.

Due to this pressure rise quenching medium iiows past the terminal 15and past the terminal 14 and out through the terminal 13, bringing abouta reliable quenching of the arcs. The ilow of quenching medium past theterminals 14 and 13 is very effective because it comprises quenchingmedium expelled from the tube 12 and not heated by the arc.

The switch pin part 7 comes into its end position in parallel with thetube 12, the guides 1t) and 11 for the switch pin remaining closed.

Due to the arrangement of the switch pin the pressure rise in thequenching chamber can have no etlect upon the switch pin movement.Furthermore the quenching operation is not unfavourably inuenced by theswitch pin movement because after a specic time it is independent of therate of switch pin movement.

Due to the pressure-generating arc burning with constant length betweenthe terminals 15 and 16 an undesired pressure rise is prevented so thatdestruction of the quenching chamber is avoided.

The lengths of the switch pin parts can be such that the upper arc isstruck later than the lower.

For the control of the issuing quenching medium the outflow opening ofthe quenching chamber can be provided with a valve which only opens at apredetermined pressure value.

Gas or liquid with or without inert powder can be used as the quenchingmedium.

In FIGURE Z-iixed contacts 21, 22, 23, 24, 25 and 26 are arranged in aquenching chamber 20 iilled with quenching medium and engage anaxially-movable switch pin comprising conducting parts 27, 28 and 29 andinsulating parts 30, 31 and 32.

The contacts 22 and 23 are electrically connected through a tube 34 andthe contacts 24 and 25 are electrically connected through a tube 35.

The switch pin slides in guides 36 and 37 and closes these guides inevery switch position.

Fixed terminals 38, 39, 4t), 41, 42 and 43 are arranged so that the gapsbetween them are shorter than the correspending gaps between the fixedcontacts.

Arcs formed between the terminals 38 and 39 and between the terminals 42and 43 are quenched by the quenching medium issuing through outilowopenings 44 and 45.

ln the central gap between the terminals 40 and 41 is formed an arcwhich serves for the pressure generation and is also subjected to thequenching action. For this purpose is provided a narrow channel 46 inorder on the one hand to generate a very effective pressure rise and on,and 24.

the other hand to subject the arc roots near the openings of the channel45 on the terminals 40 and 41 to a very edective flow of quenchingmedium.

t Spaces if/and 48 inside the'tubes 34 and 35 serve for the storage ofquenching medium which is not directly contacted by the arcs.

For the guidance of the arcs from the switch pin to the terminals thereare provided slots 50, 51 and 52 in an insulating body 53 which isprovided with spaces and passages as shown. Conducting elements maybeprovided for facilitating the guidance of the arc roots from the switchpin and the fixed contacts to the terminals, and the terminals areadvantageously placed close to the fixed contacts.

The switch is shown in the closed position, the path of the currentbeing through the contact 2i, the part 27, the Contact 22, the tube 34,the contact 23, the part 23, the contact 24, the tube 35, the contact25, the part 29, and the contact 26. A

On the opening of the switch the. switch pin is moved upwards and threearcs are drawn between the lower endsY :of the switch pin parts 27, 28and 29 and the tixed con- `tacts 22, 24 and 26.

The roots of the arcs initiated on the contacts 22, 24 and 26immediately travel to the terminals 39, 41 and 43.

On further movement of the switch pin the upper root f the centre arcjumps on to the terminal 40, before the switch pin parts 28 and 29 havereached the contacts 22 In the end position the switch pin part 2S is inparallel with the tube 47.

The three arcs now burn between the terminals 38 and 39, between theterminals 4t) and 41, and between the terminals 42 and 43. The middlearc between the ter minals 4th and 41 generates a pressure rise whichdrives the quenching medium out of the spaces 47 and 48.

The pressure rise generated by the middle aro also serves, however, toexpose this arc itself to an eifective `iiow of quenching medium. Nearthe outlet openings of the narrow channel 46 are the terminals 40 and 41on which the roots of the middle arc lie directly in the flow of thequenching medium issuing from the narrow channel 46.

The roots of all three arcs are exposed to effective currents ofquenching medium, so that eicient quenching takes place.

It will be seen that in both the illustrated switches the quenchingmedium is forced through spaces in which the terminals are arranged andwhich converge so as to guide `the medium effectively against the arcs.Each of the illustrated switches ,may be provided with one or morevalves which permit the quenching medium to ow out of rality of fixedcontacts in said quenching chamber, at least Y one fixed conductor insaid quenching chamber, each said iixed conductor interconnecting two ofsaid ixed contacts, a plurality of arc terminals attachedl one to eachend of each said fixed conductors, an axially-slidable switch pinextending through said quenching chamber in sliding contact with all ofsaid xed contacts, at least one insulating body forming slots andpassages in said quenching chamber, each said slot affordingcommunication between one of said passages and said switch pin and saidpassages leading to said arc terminals, and two switch pin guides.secured one at each end of said quenching chamber, said switch pinconsisting of insulating pin parts and conducting pin parts, thearrangement being such that in the closed condition of said switch acurrent path through said switch is completed by said iixed contacts andsaid conducting pin parts and said xcd conductors, during opening ofsaid switch said conducting pin parts draw arcs which are in series witheach other from said fixed contacts and said arcs travel through saidslots and burn in said passages with roots on said arc terminals, saidarcs being quenched by quenching medium ilowing through said passagestowards said outlets under pressure produced by the arcs themselves, andsaid switch pin in all its positions extends through and obturates bothof said i switch pin guides.

2. An 4electrical switch as claimed .in claim l, each said iixedconductor being of `open-ended tubular form with an internal spaceaccommodating quenching medium and communicating with two of saidpassages, the arrangement being such that under pressure generated bysaid arcs quenching medium from inside each said .fixed conductor isforced into one of said passages.

References Cited in the Vfile of this patent. UNITED STATES PATENTS2,477,781 Baker et al; Aug. 2, 1941 2,854,551 Lange Sept. 30, 19582,908,789 Lange Oct. 13, 1959 FOREIGN PATENTS l 878,638 France Oct'. 26,1942

